Injector chamber construction



Oct. 1, 1963 w. L. HAMILTON l 3,105,356

INJEcToR CHAMBER coNsTRucTIoN Filed April 2s, 195s 3,1ttl5,356 INECTGR CHAMBER CNSTRUCTIGN William L Harni ton, Hawthorne, Cmif., assigner to Thompson Ramo Wooldridge ine., a corporation of (litio Filed Apr. 28, 1953, Ser. No. 731,513 Claims. (Cl. eti-39.48)

The present invention relates broadly to rocket engines and the like, and is more particularly concerned with a new and improved device for eecting hypergolic ignition in reaction chambers of various types.

Reaction chambers, rocket motors and the like employing a bipropellant ignition system, and wherein an oxidizer is employed for hypergolic ignition, necessarily require a system for delivering the oxidizer to the injector at pressure. Several arrangements are utilized for this purpose, and a customary approach is to employ a mechanical pumping system or pressurization of the oxidizer reservoir.

Since it is essential for optimum results that the fuel and oxidizer make a simultaneous entrance into the reaction zone, there is required a precise and necessarily complicated synchronization device. Associated therewith are essential means for generating or causing a pressurized ow of oxidizer, with the result that the complete system is of great complexity and subject to frequent malfunctions.

it is accordingly a primary aim of the present invention to provide a device of relatively simple and reliable construction to simultaneously introduce fuel and oxidizer into a reaction chamber.

Another object of the invention lies in the provision of a starting device for rocket engines and the like, wherein the injection of oxidizer is controlled by propellant pressure.

Another object of this invention is to provide an injector chamber construction featuring an automated shutoff of oxidizer flow and the elimination of complex injector manifolding.

A further object of the invention lies in the provision of an improved rocket engine injector characterized by relatively light Weight, reuseability, and suitability for Various sizes and classes of reaction units and the like.

A still further object of the present invention is to provide a reaction chamber starting mechanism wherein the injector is integrated to the reaction chamber and advantageous elimination of superfluous plumbing, valving and external reservoirs effected, while at the same time rendering unnecessary conventional pressurizing and pumping devices to provide desired oxidizer flow.

Other objects and advantages of the invention will become more apparent during the course of the following description, particularly when taken in connection with the accompanying drawings.

In the drawings, wherein like numerals are employed to designate like parts throughout the same;

FIGURE l is a sectional view of an exemplary injector chamber construction prior to forced passage therefrom of oxidizer;

FGURE 2 is a view similar to FIGURE 1, and showing the position of parts after injection of oxidizer; and

FIGURE 3 is an end View of the starting device of this invention illustrating the structural features of the injector head.

Briefly stated, a starting device constructed in accordance with the principles of this invention comprises a pair of concentrically spaced casings provided therebetween with an annular passage communicating at one end with ports in an injector head mounting the casings. Connecting with the ports are fuel nozzles communicat- Patented Oct. 1, 1963 ing with the reaction chamber. Provided Within the inner casing is a slidable member backed by a fuel inlet and movable upon the introduction of propellant to compress oxidizer contained in the inner casing whereupon a frangible diaphragm in the injector head is ruptured and oxidizer introduced into the reaction chamber simultaneously with fuel flow through the annular passage and outwardly from the nozzles. Upon completion of travel of the slidable member, the oxidizer nozzle supporting the diaphragm is blocked by said slidable member.

Referring now to FIGURE 1, there is illustrated a starting device or injector chamber designated generally by the legend A with the parts in position prior to the simultaneous ejection therefrom of fuel and oxidizer. The chamber A in its preferred form comprises an inner tubular casing it? welded or otherwise secured at one end to an injector head 12 and surrounded in spaced relation by an outer tubular housing i4 similarly attached to the injector head. Dened by the concentrically spaced relation of the casing and housing is an annular passage 16 communicating at one end with generally axially extending bored openings or ports i3 in the injector head. In the arrangement shown, four of such ports are provided; however, the number and size of the same may be Varied to meet particular conditions.

Carried by the injector head 12 and arranged in communication with the ports i8 are a plurality of fuel injector nozzles Zt) passaged at 22 to be in substantial axial alignment with the annular passage 16 and ports 18. The nozzles 2@ are of known construction, and the fuel injected there through is ignited simultaneously with oxidizer in a reaction chamber, rocket engine or the like (not shown) positioned in communication with the injector chamber A comprising this invention.

Threadably received upon the opposite end of the tubular housing port 14 is a cap member 24 provided with an axial opening 2d into which is threaded or otherwise located a fuel inlet fitting 2S connecting with a pressurized fuel source (not shown). It may be noted that the inner casing l@ is of relatively lesser length than the outer housing port 14 to provide in the cap member 24 the radial passage 3@ in communication with the fuel inlet opening 26 and annular passage 16. As is the practice in the art, seal means 32 assure a fluid tight relation between the housing 14 and cap member 24.

Slidably movable within the tubular casing 10 is a plunger piston 34 carrying thereon seal means 36 which may be of O-ring type. The piston 34 is shaped with a body portion 38 sized to the casing inner diameter and a reduced diameter neck portion 40 sized to the diameter ofran axial passage 42 threadably receiving an oxidizer nozzle 44. As appears in FIGURE 2, upon completion of a full stroke of the piston 34, the neck portion 49 thereof is received within the axial passage 42 of the injector head 12 and effectively closes the nozzle to the further iiow there through of oxidizer contained in the tubular casing 1t?.

Oxidizer injection is controlled by fuel pressure acting upon plunger piston which compresses oxidizer within the casing to the extent that fuel and oxidizer injection occur simultaneously. To accomplish this result, the novel structure of this invention further includes a frangible diaphragm or equivalent means 46 carried by the oxidizer nozzle 44 at the outer end thereof. A relatively soft plug may be substituted for the diaphragm, or other means adapted to be ejected from the nozzle under predetermined pressure. A frangible disk is preferred, however, and may be fabricated of glass, plastic or similar material which will shatter to permit oxidizer injection through the nozzle 44 at the proper moment. The disk 3 46 may be supported along its periphery by the nozzle 44 in any desired manner.

Operation of the starting device A of this invention may be described as follows. After oxidizer has` been admitted to the casing through the passage 42 after removal of the injector nozzle 44, and the parts again assembled as shown in FIGURE 1, fuel is caused to flow through the inlet fitting 28 and into the Vpassage 26. Since the fuel is admitted under pressure, travel of the piston 34' is initiated and simultaneously fuel is directed into the radial passage 30 and annular passage 16. Continued movement of the piston compresses the oxidizer in the casing 10, and when a predetermined pressure buildup takes place, calculated to coincide with fuel injection i from the nozzles 20, the frangible diaphragm 46. ruptures and oxidizer is injected through the nozzle 44 and combines with the fuel to cause a hypergolic ignition. Continued travel of the piston occurs after initial ignition until the entire quantity of oxidizer is exhausted, at which time the piston neck portion 40 seats in the axial opening 42 and against the nozzle 44 to close off the same against possible leakage. Flow ofrfuel through the annular passage 16 and nozzle 20 then continuesuninterrupted.

Pressures of fuel flow and oxidizer compression are of course closely related to assure that the diaphragm rupture and oxidizer injection will occur at the instant desired to cause ignition. Piston travel and other factors can be calculated to accomplish this result, and as an alternative to a plunger piston, an expulsion bag structure may be employed. t

It is to be seen from the foregoing that a novel manner of causing a hypergolic start has been provided. By a mutuality of pressures between fuel flow and that required to rupture the diaphragm, oxidizer and fuel injection are accurately synchronized. No additional pressurizing or pumping devices are needed for oxidizer iiow, and superfluous valving, plumbing and external reservoirs Vare nov longer required. Complex injector manifolding is eliminated by the structure herein disclosed, and a substantial weight conservation over prior art structures is realized. Oxidizer flow is automatically shut off by the piston head and injector head construction shown in the drawings, and there is no longer a requirement for the Vcomplex injector manifolding which characterized earlier devices. Further, the principles of this invention are applicable to any size or class reaction unit, rocket motor,

or the like, and by utilization of a single injector head as herein provided, itis now possible to readily obtain a y Vcritical alignment of injector nozzles and impingement patterns. In addition, the injector chamber may be ernployed with propellants and oxidizers of various compositions, and while satisfactory results have been obtained by applicants in the ignition of hydrazine and nitric acid, the invention is not intended' to be restricted thereto.

It is to be understood that the form of the invention herein disclosed and. described is to be taken as a preferred embodiment of the same, and that various changes in the size, shape, and arrangement of parts may be effected l without departing from the spirit of the invention or the scope of the subjoined claims.

I claim as my invention: y 1. in a system for delivering fuel to a reaction chamber and including a fuel actuated starting device, a head member for a reaction chamber having nozzle means for injecting fuel into the reaction chamber, a housing connected to said head member and extending away from said head member, said housing forming a fuel passage communicating with said nozzle means, said housing having an inlet formed therein through which fuel is supplied from a source at increased pressure, and a casing forming a cylinder having its front end connected to said head member and having its rear end extending into said fuel passage in said housing, a movable piston in said cylinder having sealing means slidably engaging the walls of said casing, said piston having a motive surface against which the fuel in said fuel passage acts to move said piston from said rear end of said cylinder toward said front end of said cylinder, said head member having a filling and Vdischarge opening formed therein through which a slug of oxidizer may be charged into said cylinder for ejection by said piston into the reaction chamber, and a frangible cover means for temporarily closing said lling and discharge opening selected to reopen said opening upon the pressure of fuel in said fuel passage and acting on said piston being sufficient to inject fuel through said nozzle means, whereupon said piston will displace the slug of oxidizer through said filling and discharge opening simultaneously with the ejection of fuel through said nozzle means for hypergolic ignition of the fuel and the oxidizer, said piston being slidable into blocking relation relative to said filling and discharge opening at its forwardmost position so that continued supply of fuel through said fuel passage will discharge all fuel through said nozzle means only.

2. In a system as defined in claim 1., said housing and said casing comprising outer and inner concentrically disposed sleeves with the inner sleeve being of shorter length than the outer sleeve.

3. In a system as defined in claim 1, said frangible cover means comprising a rupturable diaphragm.

4. in a system as defined in claim 1, said nozzle means comprising an annular row of injector nozzles spaced concentrically outwardly of said filling and discharge opening.

5. In a system as defined in claim 1, said piston comprising a peripherally grooved cylindrical member and sealing rings in the peripheral grooves engaging the casing walls.

References Cited in the file of this patent UNITED STATES PATENTS 2,707,479 Thomann et al May 3, 1955 2,711,630 Lehman June 28, 1955 v 2,858,672 Clark Nov. 4, 1958 2,880,582 Turansky Apr. 7, 1959 FOREIGN PATENTS 659,802 Great Britain Oct. 31, 1951 

1. IN A SYSTEM FOR DELIVERING FUEL TO A REACTION CHAMBER AND INCLUDING A FUEL ACTUATED STARTING DEVICE, A HEAD MEMBER FOR A REACTION CHAMBER HAVING NOZZLE MEANS FOR INJECTING FUEL INTO THE REACTION CHAMBER, A HOUSING CONNECTED TO SAID HEAD MEMBER AND EXTENDING AWAY FROM SAID HEAD MEMBER, SAID HOUSING FORMING A FUEL PASSAGE COMMUNICATING WITH SAID NOZZLE MEANS, SAID HOUSING HAVING AN INLET FORMED THEREIN THROUGH WHICH FUEL IS SUPPLIED FROM A SOURCE AT INCREASED PRESSURE, AND A CASING FORMING A CYLINDER HAVING ITS FRONT END CONNECTED TO SAID HEAD MEMBER AND HAVING ITS REAR END EXTENDING INTO SAID FUEL PASSAGE IN SAID HOUSING, A MOVABLE PISTON IN SAID CYLINDER HAVING SEALING MEANS SLIDABLY ENGAGING THE WALLS OF SAID CASING, SAID PISTON HAVING A MOTIVE SURFACE AGAINST WHICH THE FUEL IN SAID FUEL PASSAGE ACTS TO MOVE SAID PISTON FROM SAID REAR END OF SAID CYLINDER TOWARD SAID FRONT END OF SAID CYLINDER, SAID HEAD MEMBER HAVING A FILLING AND DISCHARGE OPENING FORMED THEREIN THROUGH WHICH A SLUG OF OXIDIZER MAY BE CHARGED INTO SAID CYLINDER FOR EJECTION BY SAID PISTON INTO THE REACTION CHAMBER, AND A FRANGIBLE COVER MEANS FOR TEMPORALITY CLOSING SAID FILLING AND DISCHARGE OPENING SELECTED TO REOPEN SAID OPENING UPON THE PRESSURE OF FUEL IN SAID FUEL PASSAGE AND ACTING ON SAID PISTON BEING SUFFICIENT TO INJECT FUEL THROUGH SAID NOZZLE MEANS, WHEREUPON SAID PISTON WILL DISPLACE THE SLUG OF OXIDIZER THROUGH SAID FILLING AND DISCHARGE OPENING SIMULTANEOUSLY WITH THE EJECTION OF FUEL THROUGH SAID NOZZLE MEANS FOR HYPERGOLIC IGNITION OF THE FUEL AND THE OXIDIZER, SAID PISTON BEING SLIDABLE INTO BLOCKING RELATION RELATIVE TO SAID FILLING AND DISCHARGE OPENING AT ITS FORWARDMOST POSITION SO THAT CONTINUED SUPPLY OF FUEL THROUGH SAID FUEL PASSAGE WILL DISCHARGE ALL FUEL THROUGH SAID NOZZLE MEANS ONLY. 